Amphiphilic compounds for pharmaceutical or cosmetic use

ABSTRACT

The invention relates to amphiphilic compounds, for pharmaceutical or cosmetic use, consisting of an ion pair complex between an acylamino acid and a biologically active molecule. Said formed compounds enable the enhancement of the properties of pharmaceutical or cosmetic molecules, in particular of small organic molecules, peptides and proteins, nucleotides or genes.

TECHNICAL FIELD

The present invention relates to the formation and cosmetic andpharmaceutical use of an amphiphilic compound known as an “amphiphilicion pair” (or “AIP”) resulting from ionic interaction between anacylamino acid and a pharmaceutical or cosmetic active molecule.

BACKGROUND ART

The pharmacological activity of an active principle depends not only onits chemical structure and therefore its physico-chemical properties,but also on its capacity to join its active site, i.e. the locationwhere it acts in a sufficiently large quantity. This property is knownas “bioavailability”.

The bioavailability of an active principle largely depends on the routeused for its administration (enteral or parenteral route). Indeed,depending on the route of administration, the active principle canencounter obstacles which reduce its absorption; it can be dissolved toa greater or lesser extent in biological liquids, undergo a greater orlesser number of biotransformations and finally be absorbed to a greateror lesser extent. Also, it is important that the best route ofadministration is chosen for a given active principle.

The most common route of administration is the oral route. Ease ofswallowing a medicine and the fact that the digestive tract is afavourable absorption site evidently account for this choice.

However, the use of the oral route as the preferred route ofadministration means that a significant number of potentiallypharmalogically advantageous active molecules are ruled out as a resultof biotransformation problems or lack of absorption. This would lead,indeed, to the use of increased doses of actives, engendering highertreatment costs and/or increased toxicity, meaning that the productcould not be put on the market. The clinician may therefore resort to analternative administration method, such as the injectable route (SC, IM,IV).

The person skilled in the art has thus sought technical means forenhancing the protection of active molecules, i.e. increasing thequantity of compounds capable of arriving at the absorption site. He hasalso sought to alter the resorption of active molecules by acting eitheron the solubility thereof in the case where dissolution is the factorslowing down the molecule's absorption, or by improving intestinaltransmembrane passage.

With regard to improving absorption by lessening the number ofbio-transformation phenomena, the person skilled in the art hasdevelopped mainly liquid preparations such as water-in-oil emulsions,i.e. systems wherein the the hydrophilic phase is dispersed in thelipophilic phase, or multiple emulsions of the Water-in-Oil-in-Watertype.

United States patent U.S. Pat. No. 5,897,876 proposes H/L-typeemulsified systems, i.e. made up of a hydrophilic phase dispersed in alipophilic phase. These systems create a lipophilic environment aroundthe active molecule, thus enabling the quantity of resorbed molecules tobe increased. Indeed, they enable the protection of active principlesagainst the destabilising action of proteolytic enzymes andgastrointestinal fluids. This protection thereby increases the quantityof active principle arriving at its absorption site.

However, the reduced proportion of the dispersed phase (lower than 10%)of these systems limits the quantity of active principle able to besolubilised. Furthermore, the presence of ethanol in the hydrophilicpart can lead to destabilisation of the system and engender irritanteffects at cell level.

A more recent approach consists in improving absorption by increasingthe lipophilic character of the active molecules through the formationof ionic complexes. Patent U.S. Pat. No. 5,853,740 highlights theadvantage of systems using sodium dodecylsulphonate as a complexingagent. These means are used in order to improve the absorption of activemolecules which are only slightly resorbed (i.e. molecules only slightlyabsorbed at intestinal membrane level).

These complexes are made up of an ion pairing between the activemolecules of an acidic or alkaline nature and an amphiphilic compoundwith an alkaline or acidic free ionic function. The complex resultingfrom this association comes either in the form of a precipitate in thehydrophilic phase (patent WO 0132218) or in dissolved form in an organicsolvent (patents U.S. Pat. No. 5,770,559 and U.S. Pat. No. 5,853,740) ofthe ethanol, octanol, DMSO, DMF or N methyl pyrrolidone type.

One of the advantages of these complexes is that they allow thepreservation of the three dimensional structure of the active substance.Certain molecules can indeed lose their biological activity in the eventof the denaturation of this structure. These various patents indicatethat the use of such complexes can improve the bioavailablility ofactive principles.

The authors of patent U.S. Pat. No. 5,770,559 use a method of preparinga homogeneous organic solution of an active compound in which saidactive compound is not normally soluble. This solubilisation is achievedby forming a hydrophobic ion pair complex between an amphiphiliccompound and said active molecule. The complex thus obtained can betransformed into solid particles by precipitation in a supercriticalfluid, for administrations by inhalation, notably using the nasalmucosa.

As with the preceding patent, patent WO 0132218 seeks to improve thebioavailablility of hydrophilic active principles which are insoluble ina lipophilic phase, by decreasing their solubility in a hydrophilicphase and by increasing their solubility in said lipophilic phase. Toachieve this, the authors of said patent use amphiphilic counter-ions byforming an ion pair-type hydrophobic complex with the hydrophiliccompound.

The inventions relating to these patents are aimed at reducing thehydrophilic character of the active principle. The approach of thesepatents is based on decreasing aqueous phase solubility in order toincrease organic or lipophilic phase solubility. This aim is achievedthrough the formation of a hydrophobic ion pair complex. This formationresults from the complexation between an active principle and anamphiphilic compound, notably sodium lauryl sulphate (SLS), sodiumdodecyl sulphate (SDS) or a zwitterion.

The teaching of these patents is thus limited to the formation ofhydrophobic ion pair complexes. These complexes are thereforeessentially solubilised in organic solvents. These hydrophobic complexescan thus only be used with difficulty in a hydrophilic phase or in adispersed phase of the hydrophilic phase in lipophilic phase-type,notably water in oil.

Means of obtaining inorganic salts (notably sodium or potassium) ofacylamino acid have been known to the person skilled in the art sincethe 1950's. Due to their amphiphilic properties, these compounds havebeen used since this period in the field of detergents. Acylamino acidsare also used in the field of cosmetics as amino acid biovectors.

More recently, acylamino acids have been used as absorption promoters.Patent U.S. Pat. No. 5,650,386 and patents WO 0135998 and WO 0151454disclose the use of acylamino acids in pharmaceutical compositions.

Patent U.S. Pat. No. 5,650,386 describes a technique for encapsulatingactive principles. During preparation of the composition, the acylaminoacids form microspheres constituting hollow matrices inside which theactive principle is contained (or encapsulated). The active prinicipleis thus protected against various forms of degradation.

Patent WO 0135998 describes acylamino acids as absorption promotingagents, dissolved in liposome-type lipidic biphasic vesicles.

Patent WO 0151454 describes an aqueous phase mixture between anacylamino acid and an active principle. In this patent, the merepresence of acylamino acids favours absorption.

All of the previously described systems only provide incompletesolutions in the case of ionisable hydrophilic and low-permeablemolecules. Also, no teaching taken from the prior art has advocated theuse of acylamino acids to form hydrophilic phase-soluble, ion paircomplexes.

DISCLOSURE OF THE INVENTION

The aim of the present invention is thus the formation of complexesbetween a compound and an active principle, which are hydrophilicphase-soluble and thus can be used in aqueous solution directly or in aH/L type dispersed system (hydrophilic phase dispersed in a lipophilicphase).

More precisely, the object of the present invention relates to acompound for pharmaceutical or cosmetic use, formed from an ion paircomplex between an acylamino acid and a biologically active molecule,used in therapeutic or cosmetic treatments, the complex beingamphiphilic.

The interaction between the acylamino acid and the pharmaceutical orcosmetic active molecule corresponds to the interactions found withinthe complexes, also known as coordination compounds. Such interaction iscalled coordination bond, coordinate bond or even dative bond accordingto the literature. The compound resulting from this association hasamphiphilic properties and is thus known as “amphiphilic ion pair” (or“AIP”), or amphiphilic ion pair complex (or “AIP” complex).

The invention generally applies to molecules of the organic andhydrophilic type, the properties of which do not allow them to easilypass through the biological membranes, and/or which are rapidlybio-transformed in the body.

These amphiphilic compounds have the advantage of improving theavailability of active principles in the body and preserving the 3Dstructure of these active priniciples. They also have the advantage ofbeing inserted at the interfaces of dispersed systems, thus enabling theprotection of said compound of bio-transformations and extending thelifetime of the active molecules as a result thereof.

DETAILED DESCRIPTION OF THE INVENTION

More precisely, the invention applies to biologically active moleculessuch as short peptides, polypeptides, proteins, hormones, antigens,nucleotides or genes, the properties of which do not allow them toeasily pass through the biological membranes, and/or which are rapidlybio-transformed in the body. According to the invention, an “AIP”complex is formed between one of these molecules and an acylamino acid.The absorption of this molecule will thus be improved due to theamphiphilic properties of this complex.

The principal advantage in these compounds is that the presence of theacylamino acid gives them an amphiphilic character and not a hydrophobiccharacter. The “AIP” resulting from this association remains in solutionand is preferably located at the interfaces of the dispersed systems.This surprising property distinguishes complexes formed from anacylamino acid from other complexes widely formed from ions, such assodium lauryl sulphate (SLS) or sodium dodecyl sulphate (SDS), andhaving a hydrophobic character.

Thus, these complexes are preferably used for hydrophilic biologicallyactive molecules. Indeed, the latter have difficulty in passing throughthe biological membranes due to their hydrophilic property. Theamphiphilic nature of the complex thus improves the transmembranepassage of the active principle. Furthermore, this amphiphilic natureallows also the complex to be used in solution in water or in thehydrophilic phase of a dispersed system, which is impossible with ahydrophobic complex. As such, although the transmembrane passage of theactive principle is improved, it can thus still be used in hydrophilicphases.

It should be noted that in forming a complex between an acylamino acidin its native state, i.e. non-salified, and an active principle which isinsoluble in water, an amphiphilic complex which can then be solubilisedin a hydrophilic phase and still passes easily through the biologicalmembranes is also obtained.

The term acylamino acid refers to any compound resulting from anacylation between a fatty acid of natural, synthetic or modified originand a natural, synthetic or modified amino acid, the fatty acidcomprising 4-40 carbon atoms and the amino acid having at least one acidfunction and at least one free amine function. More particularly, one ofthe amine functions is located in the alpha position in relation to thecarboxylic acid function.

The following can be used as amino acids for example: aspartic acid,glutamic acid, alanine, arginine, cysteine, glycine, histidine,isoleucine, leucine, lysine, methionine, phenylalanine, proline,ornithine, taurine, threonine, tryptophan, tyrosine, serine or valine.

The following can be used as fatty acids for example: capric acid,caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid,oleic acid, linoleic acid, linolenic acid, arachidic acid, essentialfatty acids such as eicosapentaenoic acid (EPA), or docosahexaenoic acid(DHA).

Various acylamino acids are thus obtained, such as oleyl glycine,capryloyl glycine, oleyl sarcosine, lauroyl proline, oleoyl lysine,lauroyl lysine, palmitoyl phenylalanine or capryloyl serine.

According to a preferred embodiment, the amphiphilic compound resultsfrom the interaction between at least one of the reactive functionscarried by the active principle and at least one reactive function ofthe acylamino acid, generally an acid or amine function. The reactivefunction of the active principle is generally alkaline or acidic. Thisis an interaction such as previously defined in the present application,i.e. of the type of those occurring within the complexes.

The term biologically active molecules, also widely known as activeprinciples, relates to molecules having therapeutic or cosmeticproperties. These biologically active molecules can be organicmolecules, short peptides made up of 2-20 amino acids, nucleotides,genes, polypeptides, proteins, hormones or antigens.

The following can be cited as examples: amoxicillin, losartan,pravastatin, diclofenac, lidocaine, vancomicin, spiramicine, neomicin,colistine, cimetidine, ranitidine, insulin, vasopressin, calcitonin,angiotensin, secretin, heparin, growth hormone, erythropoietin,parathyroid hormone or filgastrine.

According to a preferred preparation method, said amphiphilic compoundscan be inserted into dispersed systems. The term dispersed systemsrefers to systems consisting of two immiscible phases, one generallylipophilic and the other hydrophilic, wherein one or the other of thesetwo phases makes up the dispersing phase or the dispersed phase. Theterm miscibility refers to the property whereby two compounds can bemixed together, forming a single continuous phase.

Thus, another object of the invention is a dispersed system comprising acomplex according to the present invention.

According to a preferred embodiment, the internal dispersed phase(hydrophilic or lipophilic) and the dispersing phase (lipophilic orhydrophilic) contain one or more emulsifying and/or thickening agents.

According to a particularly advantageous embodiment of the invention,the ion pair complex is obtained by mixing two phases, A and B, whichare prepared separately. Phase A contains at least one acylamino acid inthe dissolved or dispersed state and forms a mixture which is miscibleor dispersible in phase B. Phase B contains at least one activeprinciple in the dissolved or dispersed state and forms a mixture whichis miscible or dispersible in phase A.

During the incorporation of phase A into phase B, or vice versa,interaction commences between the acylamino acid and the activeprinciple such that an “amphiphilic ion pair” is formed. When phase A ismiscible in phase B, a single phase comprising the amphiphilic ion paircomplex solubilised in this single phase is obtained after mixing. Whenphase A is dispersible in phase B, a dispersed system is obtained aftermixing, in which the “AIP” complex is in solubilised form inside theinternal phase and is preferably inserted at the interfaces of thedispersed system.

According to a preferred preparation method, at least the acylamino acidor the biologically active molecule is in native form. This means thateither the acylamino acid and the biologically active molecule are bothin native form, or one of them is in native form and the other is in thesalt state.

It is also possible to isolate said amphiphilic compound in order to useit in various therapeutic compostions (tablets, gelatin capsules).

The examples given below are in no way limiting. The three firstexamples relate to methods of obtaining an amphiphilic complex accordingto the present invention. The fourth example is a permeation study of acompound according to the present invention.

EXAMPLE 1 Formation of an Ion Pair Between a Non-Salified HydrophilicActive Principle (Calcitonin) and the Non-Salified Lipoamino Acid (OleylMethyl Glycine)

Two aqueous solutions are used. The first contains calcitonin. Due tothe fact that the calcitonin is hydrophilic, the solution is clear. Thesecond solution contains oleyl methyl glycine dispersed in the aqueousphase, the oleyl methyl glycine being only slightly soluble in water.This second solution has a milky white appearance.

After mixing the first and the second solution, a clear solution havinga single phase is obtained. The obtained complex, calcitonin oleylmethyl glycine, is therefore amphiphilic.

EXAMPLE 2 Formation of an Ion Pair Between a Non-Salified LipophilicActive Principle (Lidocaine) and the Non-Salified Acylamino Acid (OleylGlycine)

Two aqueous solutions are used. The first contains lidocaine dispersedin the aqueous solution. The second solution contains oleyl glycinedispersed in the aqueous phase, the oleyl glycine being only slightlysoluble in water. This second solution has a milky white appearance.

After mixing the first and the second solution, both non-clear, a clearsolution having a single phase is obtained. The obtained complex,lidocaine oleyl glycine, is therefore amphiphilic.

EXAMPLE 3 Formation of an Ion Pair Between a Salified Active Principle(Polymyxin E Sulphate) and the Non-Salified Acylamino Acid (LinoleylGlycine).

A solution of NaOH in the quantity required for causing precipitation ofall of the polymyxin E by deplacement of the sulphate salt is added to asolution of polymyxin E sulphate. Polymyxin E, also known as colistin,thereby goes back to its non-salified, basic structure. The resultingsolution, solution B, is thus an aqueous phase with a precipitate ofpolymyxin E.

An aqueous solution, solution A, is then used which includes linoleylglycine dispersed in solution A. Due to the fact that linoleyl glycineis only slightly soluble in water, solution A has a milky whiteappearance.

Solution A is added to solution B, the solution obtained having only asingle clear phase. The polymyxin is thus resolubilized in the form ofan amphiphilic complex, polymyxin E linoleyl glycine.

It should be noted that during the first step, the active principlebeing salified with a negative ion, the sulphate ion, the precipitationof the active priniciple in its non-salified form is obtained using asoda solution. In the case where the active principle is salified with apositive ion, the precipitation of the active principle in itsnon-salified form is obtained using a hydrochloric acid solution.

EXAMPLE 4 In vitro Study of Diffusion Through a Synthetic Membrane

An in vitro diffusion study is carried out with the aim of testing howwell polymyxin E passes through a synthetic membrane. This membrane, ofnylon type, is impregnated with lipid substances, in order to simulatediffusion through the intestinal lipid membrane. This study compares theperformances of polymyxin E in the form of an ion pairing with anacylamino acid (oleyl methyl glycine) and in sulphate salified form.

The in vitro permeation study is carried out using Frantz cells. Thesecells have a donor compartment, in which a formulation containingpolymyxin E in ion pair form or a polymyxin E sulphate solution isdeposited, and a receptor compartment containing demineralised water.The measurements are carried out in 3 cells at the same time, for eachof the forms of the polymyxin E (polymyxin E sulphate or polymyxin Eoleyl methyl glycine). The two compartments are separated by thesynthetic membrane.

The measurement of the quantity of polymyxin E which diffuses throughthe membrane is carried out by UV after: 1 hour, 2.5 hours, 4 hours, 6hours and finally 7 hours.

The table below relates to a quantity of polymyxin E which diffused overthe period of time; the values shown are cumulative values. 0 h 1 h 2.5h 4 h 6 h 7 h AIP of polymyxin E- 0 0.80 2.75 4.05 5.17 6.25 oleylmethyl glycine (mg/l) Aqueous solution of 0 0.26 1.45 1.93 2.42 2.96polymyxin E sulphate (mg/l)

These results show that the ion pair Polymxyin E-oleyl methyl glycinediffuses 2 times more rapidly through a lipid synthetic membrane than inits sulphate-salified form.

1. A compound for pharmaceutical or cosmetic use comprising an ion paircomplex between an acylamino acid and a biologically active moleculesuseful for therapeutic or cosmetic treatments, said complex beingamphiphilic.
 2. The compound according to Claim 1, wherein saidbiologically active molecule is hydrophilic and non-amphiphilic.
 3. Thecompound according to claim 1, wherein said biologically active moleculeis not soluble in water.
 4. The compound according to claim 1, whereinsaid acylamino acid results from the condensation between a fatty acidof natural, synthetic or modified origin and a natural synthetic ormodified amino acid.
 5. The compound according to claim 4, wherein saidamino acid comprises at least on amine function in the alpha position inrelation to the carboxylic acid function of said amino acid.
 6. Thecompound according to claim 1, formed from an ion pair complex betweenat least one reactive function of the acylamino acid and at least onereactive function of said biologically active molecule.
 7. A dispersedsystem in which the internal dispersed phase is hydrophilic andcomprises at least one amphiphilic compound according to claim 1 and inwhich the dispersing phase is lipophilic.
 8. The dispersed systemaccording to claim 7, wherein the internal dispersed phase and thedispersing phase contain one or more emulsifying and/or thickeningagents.
 9. A method of obtaining a compound according to claim 1comprising the following steps: separately preparing a first and asecond phase, the first and second phase being miscible or dispersibleone in the other, said first phase containing at least one acylaminoacid in the dissolved or dispersed state and said second phasecontaining at least one biologically active molecule in the dissolved ordispersed state, and mixing the first phase and the second phase. 10.The method according to claim 9, wherein said acylamino acid and saidbiologically active molecule are either both in native form, or one isin native form, and the other in salt form.
 11. The compound accordingto claim 2 wherein said biologically active molecule is an organicmolecule, a short peptide, a protein, an antigen, a nucleotide or ahormone.
 12. The compound according to claim 6 wherein the reactivefunction of said biologically active molecule is an acid or aminefunction.